Australia is cutting down forests at a rate second only to Brazil and, in spite of being one of the biggest producers of greenhouse gases, has abandoned targets to reduce gases by 2000.

In 1992, Australia's emission of greenhouse gases was almost twice as high as the United States and Canada, two "high-emission" economies. The ratio is expected to get worse.

While economic and population growth has played a part, the main cause is the relentless clearing of land for farming, forestry and coastal development. The Australian Conservation Foundation, the leading environmental lobby group, says that native vegetation is being cleared at a rate of 660,000 hectares (1.58 million acres), possibly 1 million hectares, a year, a rate that is second only to Brazil.

"This has left us with the worst aspects of developed countries and the worst characteristics of the developing world," Michael Krockenberger, a foundation forestry official, said.

"The clearing has an impact not only on animals and plants, but also on the climate.

"South Australia is the only state with tough laws against clearing. Elsewhere, state governments turn a blind eye, for fear of alienating powerful farming and forestry lobbies."

Canberra has backed off imposing a "carbon tax" owing to pressure from industry. The Labor government of Paul Keating announced last week it would drop plans to impose a tax of A$1.25 (60p) a ton on emitted carbon dioxide and use part of the revenue to promote energy effiency. The scheme was designed to boost Australia's image at an international conference on climate in Berlin next month, but its abandonment means that Australia will not meet the greenhouse gas targets set at the Rio summit

Tricia Caswell, executive director of the Australian Conservation Foundation, said the organisation's members would take their campaign for a carbon tax to international forums.

"We can't believe that in the middle of what is the first decent debate about reducing Australia's greenhouse gas emissions, the federal government is taking it off the agenda."

Earlier, the foundation released a report, prepared for the Australian Academy of Technological Sciences and Engineering, which said Australia had the worst record for the emission of greenhouse gases, measured by gross domestic product, among members of the Organisation for Economic Co-operation and Development (OECD), the leading industrialised nations.

Carbon dioxide emissions grew at three times the OECD average over 20 years to 1992, while energy consumption rose by twice the average.

Vegetation acts as a "sink", absorbing carbon dioxide. Cut down and burnt, it releases carbon dioxide, and left to rot, it releases methane, a more powerful greenhouse gas. Methane emissions from sheep and cattle on vast rangelands have compounded the problem.

In an attempt to repair the damage caused by a wave of clearing during the pioneering era, the federal government has designated the Nineties the "Decade of Landcare" and has called for the planting of one billion trees. But Mr Krockenberger warned that for every tree planted, two will be cut down.